The present invention relates to an output coupler and more particularly, to such a coupler for use in industrial processes, such as soldering.
In a typical industrial process using laser beams, the laser beam is delivered to a workpiece using an optical fiber terminated by an output coupler having at least one focussing lens to achieve the required power density. However, some processes, such as soldering and desoldering the output leads of resistor or capacitor blocks, when performed using a single laser to solder one lead at a time, result in a tilting up of one end of the device away from the circuit board, a process called "tombstoning". This can be prevented on large workpieces by using a plurality of optical fibers and respective output couplers to solder opposing pairs of output leads. However, this cannot be done on small integrated circuits due to the very small spacing between the leads and the large size of the output coupler due to the focussing lens. It is known from U.S. Pat. No. 4,799,755, to have an output coupler for a single optical fiber without any focussing lens at the output of the coupler. However, if the process requires multiple positions and angles with respect to the workpiece, the entire coupler must be moved, which is awkward.
It is therefore an object of the present invention to provide a plurality of laser beams in a small space with the distance between the beams and their angles conveniently adjustable.